The invention relates-to a multiway valve, comprising a chamber being delimited by at least two substantially plane-parallel surfaces, into which at least three feed or discharge ducts open out, the state of being open or closed of the ducts being affected by the positioning of a member, which member is accommodated inside the chamber in such a manner that it is moveable in two dimensions in a plane which runs parallel to the plane-parallel surfaces, the member being flattened on two sides, the said flat sides of the member interacting in a sealing manner with the plane-parallel surfaces by means of surface contact, and which member can be made to interact in a sealing manner with one or more duct openings, and control means for moving the member inside the housing.
A multiway valve of this kind is suitable for controlling, metering and mixing fluid flows through multiple feed or discharge ducts, and is known from DE-A-2 140 484. However, a plurality of pull and push rods are arranged around the chamber, penetrating the chamber in order to move the member.
The invention intends to improve the valve of the prior art, and is characterized in that the member comprises a permanent magnet and the control means comprise a plurality of magnet-actuating assemblies which are disposed stationarily around the chamber and comprise electromagnets with a soft iron core, which assemblies are designed to generate a magnetic field which attracts or repels the member.
As a result, there is no need for any mechanical connection between the control means and the member, providing a multiway valve which is virtually maintenance-free and is scarcely susceptible to wear.
Preferably, the control means of the multiway valve according to the present invention comprise a plurality of units which are disposed radially around the chamber and at substantially equal angles with respect to the centre of the chamber. An arrangement of this nature allows the member to be moved via uniform transmission of force and accurate control.
Preferably, the member is controlled in such a manner that its position is changed via a substantially rectilinear movement.
The magnetic field lines of the permanent magnet are advantageously directed substantially in the same direction as those which can be generated by the magnet-actuating assemblies.
By energizing an electromagnet with a resultant magnetic polarity which is oppositely directed to that of the permanent magnet of the member, the member will be attracted by the electromagnet. Due to the fact that the member comprises a permanent magnet, this magnet will attract the two pole shoes of the electromagnet; depending on the magnetic strength selected for the permanent magnet and the position of the pole shoes, the member can be held in the position obtained by the attraction by the energized electromagnet. Thus, the electromagnet in question can be switched off after a short energizing pulse, and then the member maintains its adopted position due to its own magnetism. As soon as the member is to adopt a different position inside the chamber, a different electromagnet can also be energized with a short pulse, so that the member will be attracted by this electromagnet and its position will be changed accordingly. The member will again continue to hold its newly adopted position. In order to facilitate the displacement of the member, the polarity of the first electromagnet can be reversed. In this way, as a resultant, a force is generated on the member which is directed away from the centre axis of the poles of the electromagnet, resulting in the member being repelled by the said electromagnet. An arrangement of this nature makes it possible to provide a multiway valve which is readily accessible, is extremely energy-efficient, reacts rapidly and reliably and is simple to operate automatically. There are no limits to the possible applications; a multiway valve of any desired dimensions can be used depending on the desired application. The only limitation on the multiway valve when using magnets lies in the limited applications in the case of magnetizable fluids.
In GB-A-2 274 898, a pipeline pig of magnetisable material is described, that can be moved through a pipeline with the aid of electric coils, each wound around a region of the pipeline. At a Y-junction of the pipeline, the pig can be directed into the intended pipe by energizing the particular coil at the said pipe.
DE-A-1 282 402 discloses a two-way magnetic valve, wherein the valve member is magnetic and movable between two poles of a single electromagnet. By reversing the polarity of the magnet, the valve member is moved from the one pole to the other pole of the electromagnet.
In the valve according to the present invention, one or more ducts will be closed off as a function of the position of the member. By changing the position of the member, it is possible to close off different or additional ducts; in addition to complete closure, the member may also be positioned so as to partially close off one or more ducts, resulting in an additional metering function.
By allowing the ducts to open out into the chamber at suitable positions, it is possible to achieve a large number of possibilities for the controlled closure and opening of specific combinations of ducts in order to control, mix and meter various feed streams.
Preferably, the magnet-actuating assembly is positioned in such a manner that the centre axis of the two pole shoes runs inside the chamber, the distance therefrom to the closest transverse wall of the chamber being less than or equal to the shortest distance from the magnetic centre of the member to the said transverse wall. By such a positioning of the magnet-actuating assembly, given a magnetic field generated by the said assembly, a magnetic force is exerted on the member which is directed towards the closest transverse wall. If the multiway valve is designed in such a manner that the member closes off or opens a duct opening in the said position, it is advantageous for the said distance from the centre axis to the closest transverse wall of the chamber to be shorter than the shortest distance from the magnetic centre of the member to the said transverse wall; a constant radial force in the direction of the closest wall is exerted on the member for as long as the member is to remain in the said position, thus ensuring the correct position of the member and the correct function of the multiway valve. If the said distances are equal, the assembly will not exert a radial force on the member and the member will only be held passively in this position.
In the case in which the member closes off a duct opening by direct interaction with a transverse wall of the chamber, in the above-mentioned case the shortest distance from the magnetic centre of the member to the transverse wall will be determined by the diameter and the shape of the member and the position of the magnetic centre therein; however, if the member interacts with a closure body or opening body as described above, the distance is partly determined by the shape and the configuration of this body. Magnetic centre is intended to mean the centre point of the magnetizable material of the member.
If one or more duct openings are incorporated in the transverse walls, it is highly advantageous, in order to achieve optimum immediate closure, if the centre axis through the pole shoes of the magnet-actuating assembly intersects a radial axis of the chamber through the duct opening. In this way, the magnetic force resultant will be directed directly onto the duct opening in question, ensuring successful closure, which is especially advantageous if the multiway valve comprises a plurality of magnet-actuating assemblies which comprise electromagnets with a soft-iron core.
In an attractive embodiment of the multiway valve according to the invention, the field lines of the permanent magnet of the member run radially with respect to the member and the magnet-actuating assemblies are designed to generate a magnetic field whose field lines run substantially parallel through the plane of movement of the member. A magnetic field of this nature will be referred to below as a xe2x80x9cparallel magnetic fieldxe2x80x9d. In this arrangement, a maximum possible force transmission from the magnet-actuating assemblies to the member becomes possible. This method is illustrated diagrammatically in FIG. 7b. 
The member of the multiway valve may also comprise a permanent magnet whose field lines run axially with respect to the member, in which case the magnet-actuating assemblies are designed to generate a magnetic field whose field lines are transverse with respect to the plane of movement of the member. A magnetic field of this nature will be referred to in this application as a xe2x80x9ctransverse magnetic fieldxe2x80x9d. This method is illustrated diagrammatically in FIG. 7a. If desired, the transverse magnetic field may run through a selective area of the chamber, under the influence of which the member can be attracted and consequently can adopt a position inside the chamber which is such that it closes off or opens one or more channel openings. By displacing the transverse magnetic field, the position of the member inside the chamber will be changed accordingly, with the result that, for example, a different duct opening is closed off or opened. Although the force resultant in the direction of movement of the member will be considerably lower in the case of a transversely applied magnetic field compared to a parallel magnetic field, the member can be positioned very accurately within the chamber using the arrangement in which transverse magnetic fields can be generated. In order to generate a transverse magnetic field so as to influence the movement of the member inside the chamber, the magnet-actuating assembly is preferably disposed in such a manner that the centre axis of the pole shoes thereof is at right angles to the centre longitudinal plane of the chamber, the distance from each of the two pole shoes to the said centre longitudinal plane being equal. An arrangement of this nature will cause the magnetic field to be transverse with respect to the plane of movement of the member inside the chamber and will cause the force exerted by one pole shoe on the member to be of the same magnitude as but oppositely directed to the force exerted by the other pole on the member. For this purpose, it is necessary for the magnetically conductive material to be arranged mirror-symmetrically in the member with respect to the plane of the direction of movement of the latter. Thus the sum of these forces, axially with respect to the centre axis of the two pole shoes, is zero, and the resultant of the attraction force on the member is directed towards and radially with respect to the centre axis of the pole shoes. The force resultant thus lies in the plane of movement of the member. Due to this force resultant, the member will move towards the centre axis of the said pole shoes. As soon as the member, or at least the magnetically conductive material thereof, is centred around the centre axis between the pole shoes, the radial force resultant will also be zero.
The possible combinations of a specific fluid feed and a large number of different discharges can be increased by, for example, branching a general feed duct or discharge duct and allowing the branched ducts to open out into the chamber at a distance from one another which is such that at least one of the branched feed openings will be open in any position of the member inside the chamber. Likewise, a plurality of discharge ducts may be joined together integrally in a wall and/or outside the valve downstream of the multiway valve, in order to discharge a large number of combinations of fluids, which can be fed through various ducts, to one or more branches of a common discharge without interruption.
The chamber may have any possible form, such as for example a round chamber in which a spherical member is enclosed virtually without any free space, which sphere can be rotated inside the chamber through two directions of rotation which are perpendicular to one another. Thus the chamber may also have a flattened form, in which case the member is preferably accommodated inside the chamber in such a manner that it is moveable in two dimensions in a plane which runs substantially parallel to the longitudinal axis of the chamber. The member can thus be moved in the length and width directions inside the chamber. The member may preferably adopt any possible position inside the chamber.
The chamber is delimited at least by two substantially plane-parallel surfaces, the plane in which the member can move being parallel to the plane-parallel surfaces.
Both surfaces are preferably connected by side walls, resulting in a closed chamber. An xe2x80x9copenxe2x80x9d chamber, in which one or more side walls are discontinuous, is also possible, however; in this case, the member has to interact with the chamber walls in such a manner that it is impossible for any uncontrolled loss of fluid to occur through the openings. An open structure of this nature may be advantageous by dint of ease of access and inspection possibilities.
The ducts may open out into the chamber in such a manner that the direction of movement of the member is substantially perpendicular to the fluid feed or discharge direction, for example by allowing the ducts to open out into one of the plane-parallel surfaces. This means that relatively low levels of force are required to change the position of the member inside the chamber.
The member is flattened on two sides in order to ensure satisfactory sealing of the ducts which are arranged in the plane-parallel surfaces and open out into the chamber. It is also possible, in this way, to obtain sealed interaction with both the top and bottom sides of the chamber, which is important, for example, in the case of the above-mentioned xe2x80x9copenxe2x80x9d structure of the chamber.
The member may be made, for example, from metal, plastic or a ceramic material, although other materials may also be suitable, as long as the above-mentioned seal is effectively provided.
In a preferred embodiment, the member comprises, at least at the location of one of the flattened sides, a cavity which is delimited by the top or bottom surface of the chamber which interacts with the said side of the member, into which surface a central duct opens out, which opening is in communication with the member cavity, irrespective of the position of the member in the chamber.
By designing the member in such a manner that it defines a cavity, this cavity may itself function as a chamber in order to place two or more ducts in communication with one another. By dimensioning the chamber in such a manner that the cavity is in communication with one or more ducts to a certain extent at various positions of the member inside the chamber, it is possible to use the said duct as a central feed or discharge, so that this flow is controlled and/or mixed. The member may then be positioned in such a manner inside the chamber that the said central duct is in communication, via the member cavity, with one or more other ducts, it being possible, by moving the member, to interrupt a connection to a greater or lesser extent and/or to bring about a connection to one or more other ducts to a greater or lesser extent. Obviously, it is also possible to close off the other ducts, whether or not together with the central duct, depending on the position of the duct openings in the chamber, the shape of the member cavity and the position of the member. The member preferably comprises a continuous ring section which interacts in a sealing manner with at least one of the plane-parallel surfaces, the member cavity being delimited in the radial direction by the inner circumference of the ring section. This provides a substantially round cavity, allowing a large number of connection combinations between feed and discharge ducts by means of relatively simple movements of the member.
Advantageously, the member cavity is in communication with both the top and bottom sides of the chamber. As a result, it is also possible, via the member cavity, to place ducts which each open out at opposite plane-parallel surfaces of the chamber in communication with one another. This allows the valve to be of compact design and reduces the restriction for the controlled flow. Advantageously, the inner walls of the cavity in the member are designed to be convex, thus reducing turbulence in the fluid flow.
Advantageously, cavities are formed on both the bottom and top sides of the member, in which case the two cavities are not in communication with one another, so that the two separate fluid flows can be controlled simultaneously with very reliable control of the two flows in identical directions and volumes.
Advantageously, a central cavity is made on the top side of the member and a concentric annular cavity is made on the bottom side, the two cavities not being in communication with one another, so that two fluid flows can be controlled simultaneously, ensuring with great reliability that the control of one flow is the inverse of the control of the other flow.
Obviously, it is possible, in a similar manner, to make a plurality of concentric cavities in the member, resulting in a large number of possible connection combinations. A few examples are illustrated in FIG. 8. The control of all these combinations is linked to the position and shape of the member.
The degree of freedom in the number of possible connection combinations can, furthermore, be expanded by a further embodiment of the invention in which the member comprises at least two continuous ring components which are arranged on top of one another and each interact in a sealing manner with a plane-parallel surface and with one another by means of surface contact, which ring components, independently of one another, can be moved with respect to the plane-parallel surfaces, the spaces inside the continuous ring components being in communication with one another and defining the member cavity. By arranging the member in the form of a plurality of ring components which are arranged on top of one another, such as continuous annular discs, it is possible to obtain a multiplicity of possible connection combinations if the relevant ducts are arranged in both the top and bottom sides of the chamber. For example, if the member comprises two continuous annular discs and a plurality of ducts in mutually opposite plane-parallel surfaces, it is possible to connect together one or more duct openings which open out into the same surface or into an opposite plane-parallel surface (or can be closed off from one another). It is important, for the effect mentioned above, for it to be possible to place the space defined within one ring component in communication with that of the second ring component. The member cavity is thus define by the spaces which are in communication with one another. If desired, the communication between the two spaces may be interrupted by sliding the two ring components apart, in order to disconnect certain connection combinations or to form two independent connection circuits. By sliding the two discs sufficiently far over one another, it is possible to combine the said circuits.
In an attractive embodiment, the control means comprise a rod which is guided through a surface delimiting the top side of the chamber and engages on the top side of the member.
In another embodiment of the invention, one of the discs is accommodated rotatably in the chamber and comprises at least one bore which puts the member cavity in commmunication with a side wall or with a plane-parallel surface which interacts with this disc. It is thus unnecessary for both discs to be able to move in two dimensions inside the chamber; by providing one of the discs with a continuous bore and accommodating it rotatably inside the chamber, it is possible to bring about a large number of connection combinations. A rotatable arrangement is regarded as a one-dimensional movement. For this purpose, the bore in the said disc, by rotating the said disc, can be connected to a connected duct which is situated, for example, in a side wall, with the result that this duct can be placed in communication with the member cavity.
By accommodating one or more feed or discharge ducts in the side wall(s) of the chamber, it is possible to increase the number of connection combinations still further. Even if the member does not have any bores or other radial openings allowing these ducts to be connected to the member cavity, the ducts present in the side wall can be either closed off by the member or connected to other ducts which are present in the side wall or in the plane-parallel surfaces. The multiway valve therefore allows two combination circuits: a circuit in which ducts are connected to one another via the member cavity and a second circuit in which ducts which are neither closed off by the member nor in communication with the member cavity are connected to one another.
A duct may advantageously be closed off by the fact that at least a section of a side wall of the member interacts in a sealing manner with the transverse wall(s) of the chamber around a duct opening. However, it is also possible for a separate closure body, which is held in the open position by spring pressure, for example, to be positioned in front of the duct opening in question. The member can thus move the said closure body counter to the spring stress until it interacts in a sealing manner with the duct opening. For example, it is conceivable for there to be configurations in which the duct opening is provided with an opening body which, in a similar manner to that described above, closes off the duct opening, for example by means of spring pressure, it being possible for the member to be made to interact with the opening body, with the result that the duct in question is opened. In a preferred embodiment of the multiway shut-off valve according to the present invention, the member may be made to interact in a sealing manner with one or more duct openings.
In order to improve the above mentioned interaction between the side walls and the member further, at least one side wall of the member is of convex design and the transverse walls of the chamber are of correspondingly concave design at least in the vicinity of the duct openings which are present therein.
In order to ensure correct movement and positioning of the member inside the chamber of the multiway valve, the corners between the transverse walls are preferably rounded with a defined radius and the member is correspondingly rounded, at least locally, with a diameter which is equal to or less than twice the said radius.
The invention furthermore relates to a method for actuating a multiway valve according to the invention with the aid of one or more magnetic fields, wherein one generates a magnetic field with at least one magnet-actuating assembly, in order to move the member, under the influence of the magnetic field into a position inside the chamber which opens or closes at least one duct opening. It is thus possible to generate a transverse or parallel magnetic field, so that the member is moved, under the influence of the magnetic field, into a position inside the chamber which allows at least one duct opening to be opened or closed off.
Preferably, the electromagnet is energized in such a manner that it attracts or repels the permanent magnet, the member closing off or opening at least one duct opening.
Preferably, the magnetic strength of the permanent magnet of the member is selected in such a manner that the latter, once it has been attracted by an energized electromagnet, maintains the resultant position inside the chamber when the electromagnet has been switched off due to the attraction between the permanent magnet and the pole shoes of the switched-off magnet. The member, by means of its permanent magnet, will attract the pole shoes of an electromagnet which is switched off, so that there is no need for an electromagnet to be permanently energized. All that is required to displace the member inside the chamber is for another magnet-actuating assembly to be briefly energized sufficiently to overcome the attraction force between the member and the first switched-off electromagnet. The member is then moved towards the energized electromagnet and, after the electromagnet is switched off, again maintains its position into which it has been moved by the said energized electromagnet until another electromagnet attracts the member as a result of being energized.
If it is desirable for the position of the member inside the chamber to be changed, the magnet-actuating assembly is advantageously energized with reversed polarity, so that the member reverses the opening or closure of the duct opening. By reversing the polarity, the electromagnet will be made to repel the member, so that the latter is driven out of its position in which it was originally positioned by the attracting energization.
Highly advantageously, various magnet-actuating assemblies of a multiway valve are energized simultaneously, in such a manner that one assembly attracts the member and the other assemblies repel the member. In the event of an actuation of this nature, the member is guided inside the chamber, as it were towards the desired position, due to the fact that the resultant force for displacing the member is intensified by the repelling magnetic fields. Furthermore, relatively weak energizing pulses are sufficient to displace the member from a certain position to another position inside the chamber of the multiway valve.
In order to achieve accurate actuation, it is advantageously possible to dispose a plurality of magnet-actuating assemblies in the multiway valve and to energize them in such a manner that they repel the permanent magnet, the positioning of the member being influenced by varying the magnetic field strength of one or more magnet-actuating assemblies. Due to the fact that all the magnet-actuating assemblies repel the member, the member will be moved towards the magnet-actuating assembly which is repelling the member the least. By changing the magnetic field strength of one or more of the magnet-actuating assemblies, the position of the member will be changed accordingly. However, in this embodiment it is necessary for the magnet-actuating assemblies in question to be energized continuously.